A contractor estimates that 5 persons could plumb Ravi's house in 8 days. If he used 6 persons instead of 5, how long should they take to complete the job .

Question

$\begin{array}{1 1} 6 \large\frac{2}{3} \\ 6 \\ 7 \\ 7 \large\frac{2}{3} \end{array} $